SENSIBLE NOTE, in Music, is that which constitutes a third major above the dominant, and a semitone beneath the tonic. Si, or B, is the sensible note in the tone of ut or C sol ♯; or G sharp, in the tone of la or A.
They call it the sensible note on this account, that it causes to be perceived the tone or natural series of the key and the tonic itself; upon which, after the chord of the dominant, the sensible note taking the shortest road, is under a necessity of rising; which has made some authors treat this sensible note as a major dissonance, for want of observing, that dissonance, being a relation, cannot be constituted unless by two notes between which it subsists.
It is not meant that the sensible note is the seventh of the tone, because, in the minor mode, this seventh cannot be a sensible note but in ascending; for, in descending, it is at the distance of a full note from the tonic, and of a third minor from the dominant.